This research is concerned with regulation of salivary gland growth and functon. An aspect of function which will be studied in the next year involves regulatory effects of calcium on transport of sodium and potassium by salivary ductal epithelium. In the proposed experiments, main excretory duct of rat submaxillary gland, perfused through the lumen, will serve as the experimental system. The concentration of calcium in the luminal perfusion medium will be changed; samples of perfusate will be collected and analyzed for sodium and potassium. At the same time, water movements across the duct will be monitored, by measuring changes in inulin concentration in samples of luminal fluid during perfusion. Thus, the relationship of net flux of sodium and potassium to the luminal concentration of calcium will be determined. With regard to growth responses, it is planned to delineate the autonomic pathways which regulate the mitotic response induced when the level of glandular secretory activity is changed. In this regard, selective surgical or chemical denervation of the rat parotid gland will be employed. These investigations will be made when glandular activity is reduced (by liquid diet) from normal and then again increased to normal by the substitution of solid chow for the liquid diet. They will also be made on glands where the functional activity is increased from normal to above normal. Thus, the role of these pathways in an induced mitotic response will be delineated.